I am using and X10DRI-T4+ with 24 x 32GB 2400 MHz RDIMM memory modules but I am only seeing that the memory speed is 1600 MHz. How can I get the memory to run at 2400 MHz?
The 1600 MHz is the maximum memory speed that can be achieved with the memory configuration that you have. This configuration will have 3 DIMMs sharing the same channel and in that case, the memory will run at the 2nd lowest speed from the max speed which would be 1600 Mhz. You can find more details starting on page 2-14 of the user manual: https://www.supermicro.com/manuals/motherboard/C600/MNL-1560.pdf